A topic in the Open Knowledge Graph — a free, open map of 15,290 topics and the order to learn them in.
APR (Annual Percentage Rate) and APY (Annual Percentage Yield) both express interest rates but differ in how they account for compounding. APR is the simple annual rate without compounding; APY includes the effect of compounding and represents the true annual return. This distinction significantly affects borrowing costs and savings returns over time.
Calculate APR and APY for a sample loan and savings account. Use online calculators to compare the same nominal rate under APR vs. APY to see the compounding effect.
APR and APY are interchangeable (they account for compounding differently). Higher APR always means higher actual cost (APY reveals the true cost).
You already understand compound interest: when interest is added to a balance and then earns interest itself, the growth accelerates over time. APR (Annual Percentage Rate) and APY (Annual Percentage Yield) are two ways of expressing how much interest applies to a financial product annually — but they treat compounding very differently. APR ignores compounding and simply states the periodic rate multiplied by the number of periods. APY captures the full effect of compounding and tells you what you actually earn or pay over a year.
Here's a concrete example. Suppose a savings account advertises a 6% APR, compounded monthly. The monthly rate is 6% ÷ 12 = 0.5%. After 12 months of compounding, $1,000 grows to $1,000 × (1.005)12 ≈ $1,061.68. The APY is therefore about 6.17% — not 6%. The gap seems small, but it widens significantly at higher rates or when compounding happens more frequently (daily vs. monthly). This is why APY is the honest number: it tells you what you'll actually end up with. When comparing savings accounts or certificates of deposit, always compare APYs, not APRs.
The same arithmetic applies in reverse for borrowing, but now you're the one paying the interest. A credit card with a 24% APR compounded daily has an APY of about 27.1%. The advertised APR looks lower than the true annual cost. Lenders are legally required to disclose APR under the Truth in Lending Act in the U.S., which means the advertised number is often the one that makes the product look more attractive. Savvy borrowers convert APR to APY to understand the real cost: APY = (1 + APR/n)n − 1, where n is the number of compounding periods per year.
The strategic implication is straightforward: when you're saving, look for the highest APY. When you're borrowing, look for the lowest APY (even if the lender advertises APR). The same 5% stated rate can translate to very different real costs depending on how often the interest compounds. For mortgages and auto loans with monthly payments, the math is more complex because principal reduces over time — but understanding APR vs. APY is the foundation that makes those more advanced calculations interpretable.